Welcome to the forum. I have a TM, so cannot comment on the Friendship, as far as issues unique to that model.
If you do not have the service records for that coach:
You have an air-line dryer on the air brakes that may need changing.
You have a filter on the power steering line that may need changing.
Oil, air, and fuel filters x 2 all may need changing.
Your Allison trans is at its required 50K service, filters and possibly fluid.
Generator may need service.
Check the water in your batteries.
Check the hydraulic fluid in your power slides/levelers.
The Cummins is rock solid, as is the Allison Trans. Go to the Freightliners web site: http://www.freightlinerchassisownersclub.org/
to see it there are any recalls for your chassis/engine/trans.
Also, Family Motor Coach Assn is a great site for information. http://www.fmca.com/
Oh, have your steering linkage set up checked.
Sounds like a lot, but prevention is the best policy.